Pruner

ABSTRACT

A pruner having a pair of pivoted handles with opposed confronting surfaces. A rotary latch with a latching finger mounted in a transverse opening in one handle engages a recess in the confronting wall of the other. The recess is formed on an arc about axis of latch and the engaging surface of the latch finger is formed on an arc about an axis offset from the latch axis to provide wedging engagement with the recess. Resilient bifurcated legs on the latch pass over center to a latching position and a force urging the handles apart produces a force on a moment arm to two axes to urge the latch through the overcenter position by a snap-action to assume an unlatched position.

United States Patent Johnson Dec. 4, 1973 PRUNER [75] Inventor: EdwardJ. Johnson, New Britain, 'f' Exami' wr Othe Slmpson Conn AsszstantExaminer-J. C. Peters Attorney-John M. Prutzman et a1.

[73] Assignee: The Stanley Works, New Britain,

Conn. [57] ABSTRACT 22 Filed; Jam 31 1972 A pruner having a pair ofpivoted handles with op- Appl. No.: 221,923

posed confronting surfaces. A rotary latch with a latching fingermounted in a transverse opening in one handle engages a recess in theconfronting wall of the other. The recess is formed on an are about axisof latch and the engaging surface of the latch finger is formed on anarc about an axis offset from the latch axis to provide wedgingengagement with the recess. Resilient bifurcated legs on the latch passover center to a latching position and a force urging the handles apartproduces a force on a moment arm to two axes to urge the latch throughthe overcenter position by a snap-action to assume an unlatchedposition.

6 Claims, 4 Drawing Figures PRUNER This invention relates to a prunerand more particularly to a pruner having an improved latch.

An object of this invention is to provide an improved pruner having alatch which prevents the accidental opening of the pruner.

A further object of this invention is to provide a pruner incorporatingan accident-free latch which also accommodates the opening of the prunerwithout the manual actuation of the latch.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

A better understanding of the invention will be obtained from thefollowing detailed description and the accompanying drawing of anillustrative application of the invention.

In the drawing:

FIG. 1 is a side elevation view, partly broken away, of pruner embodyingthe present invention;

FIG. 2 is an enlarged fragmentary view, partly broken away, of the latchof the present invention;

FIG. 3 is a further enlarged fragmentary cross sectional view takenalong the lines of 33 of FIG. 2, and

FIG. 4 is a still further enlarged fragmentary view, partly in section,taken along the line 44 of FIG. 3.

Referring now to the drawings, there is shown an exemplary prunerillustrative of the present invention, which comprises a pair of handles10,12, formed of a molded plastics material, such as reinforced nylon,secured together by a bolt 14 which serves as a pivot for the handles.

Handle is provided with an integral forward extension which provides ananvil 16 for a separable apertured blade 18 mounted by the handle 12 andthe pivot The rearward portion 20 of pivoted blade 18 abuts a shoulder22 of the handle 12 to prevent relative rotation of the blade 18relative to handle 12. A resilient roll pin 24, fixedly mounted in atransverse aperture in handle 12 adjacent the shoulder 22, engages therear edge of blade 18 and supports the compression forces and shockloading when a plant clipping is being severed between the cutting edge26 of the blade and the anvil 16.

The handles 10,12 are biased to an open position by a torsion spring 28positioned around the pivot 14 so that the pruner is automaticallyreopened upon removal of the closing pressure on the handles.

The handle 12 is provided with a transverse cylindrical recess 30 whichis partially open to an arcuate wall 32 of handle 12. The arcuate wall32 confronts and is adjacent to the arcuate wall 31 of handle 10 whichgenerally describes an are about the axis of pivot 14 as best shown inFIG. 1.

Mounted in the recess 30 is a latch 33, molded from a plastics materialsuch as delrin, having a cylindrical bearing portion 34 joumaled in thecylindrical recess 30. A bushing 38 is press-fit in a cylindricalintermedi ate portion 36 (FIG. 3) of reduced diameter. Bushing 38 isprovided with a generally diamond shaped aperture 40 and with anexternal protrusion 42 which engages a complementary recess 44 of thehandle 12 to index the diamond shaped recess 40 as required in thepractice of this invention.

The closed end of the recess 30 is further stepped at 46 to provide acylindrical bore 48 beyond the end of the bushing 38 for purposeshereinafter more fully described.

The latch 33 is provided with a lever 50 for the manual rotation of thelatch about the axis of the cylindrical bearing surface 34 of the latch.The latch is further provided with a latching finger 52 having anarcuate outer end 54 formed on a radius about the center 56 (FIG. 4).

A recess 60 (FIG. 4) is formed in the wall 31 of the handle 10 and isprovided with an arcuate bottom wall 61 which generally describes an arcabout the axis 62 of the cylindrical bearing portion 34 of the latch 33.The recess 60 is provided with an end wall 64 to limit the rotation ofthe finger 52 into the recess under latching conditions.

As best shown in FIGS. 3 and 4, a bifurcated extension 66 is providedatthe free end of the latch 33 to provide a pair of legs 68 havingdepending feet 70,72 respectively, which are positioned in bore 48 withthe ends of the feet engageable with the bushing 38 to maintain thelatch assembled with the handle 12. The bifurcated extension 66 isprovided with radial projections 74,76 which are triangular in crosssection, to provide pointed tips 78,80 which are inherently biased intothe corresponding recess 82,84 of bushing 38 when the latch is in itsunlatched position. By virtue of the diamond shaped aperture 40 of thebushing 38, it is readily apparent that the latch 33 may be assembledwith the handle 12 when the feet 70,72 of the latch are aligned with therecess 86,88, respectively, of the bushing due to the inherentresiliency provided by the bifurcated legs 68 of the latch. Onceassembled the shoulders 90, 92 of handle 12 serve as stops for thefinger 52 to limit the rotation of the latch.

In operation, with the handles in the closed position, the latch 33 maybe rotated clockwise from the position shown in FIG. 4 to move thefinger 52 to the position shown in FIG. 2. Since the end of the finger52 has a smaller radius of curvature than wall 61 of the recess 60, thefinger 52 of latch 33 may be rotated into the recess with a wedgingaction to maintain the handles in their fully closed position despitemanufacturing variations and tolerances and to assure a tight orinterference fit between the finger and the wall 61 of recess 60.

In latching position, the tip is positioned as shown in phantom lines ofFIG. 4 so that a line through the axis 62 of the latch 33 and the tip 80is rotated slightly past a right angle relationship with the surface 96of the diamond shaped aperture of bushing 38, say 5, to provide asnap-action latching and to maintain the finger 52 in its latchedcondition to prevent accidental unlatching upon an involuntary squeezingof the handles 10,12.

A feature of this invention is that the pruner may be unlatched withoutmanual actuation of the latch by the simple expedient of pulling thehandles apart. When the handles are pulled apart the force applied tothe ar-' cuate end 54 of the latching finger 52 by the wall 61 of notch60 by the relative rotation of handle 10 is directed at approximately a45 angle relative thereto. A line through the centers 56, 62 passesbeyond the end of latching finger 52 so that a moment of force isapplied to the latch to rotate it counterclockwise about its pivot axis62. When this force is sufficient to overcome the forces retaining thelatch in its latching position, the bifurcated legs 68 of the latch willbe moved overcenter and unlatch. Thus, the latch design is one in whichthe pruner is held against inadvertent opening upon the squeezing of thehandles while at the same time is of a design in which it is possible tooverride the latch without permanent deformation or damage by pullingthe handles apart so that the latch has a long operating life despitethe abuse which may be imposed on a pruner latch by the user.

As will be apparent to persons skilled in the art, variousmodifications, adaptations, and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

I claim:

1. In a tool of a pivoted crossed lever type, first and second handlespivotally connected to one another, said first and second handles havingrespectively pposed first and second surfaces adjacent the pivot axistherebetween, one of said handles having a recess in said opposedsurface thereof and the other of said handles having a rotary latchhaving a latching finger engageable with said recess, overcenterretaining means for retaining the latch in its latched position, andmeans associated with said latching finger and said recess to overridesaid retaining means and move said latching finger to its unlatchedposition upon the application of a manual force on said handles urgingthem to an open position.

2. The tool of claim 1 wherein the latching finger has a wedge-shapedengaging surface, and the manual opening movement of said handlesimposes a force thereon at a small acute angle when the latch is in alatched position.

3. The tool of claim 2 wherein the engaging surface of said latchingfinger is formed on a radius of curvature having a center which isoffset from the pivot axis of the latch.

4. The tool of claim 3 wherein the radius of curvature of the engagingsurface of said latching finger is less than its distance from the axisof said latch.

5. The device of claim 3 in which the force applied to said latchingfinger upon the application of a force urging the handles to an openposition is directed at an angle of about 45 thereto and is offset froma line passing through the center of curvature thereof and the axis ofsaid latch.

6. The tool of claim 3 wherein the rotary latch is journaled in anaperture and is provided with resilient depending leg means biasedagainst a non-circular wall of said aperture and the contacting portionof said leg means is rotated slightly past a line which is perpendicular to said non-circular wall and passes through the axis of rotationof said latch.

1. In a tool of a pivoted crossed lever type, first and second handlespivotally connected to one another, said first and second handles havingrespectively opposed first and second surfaces adjacent the pivot axistherebetween, one of said handles having a recess in said opposedsurface thereof and the other of said handles having a rotary latchhaving a latching finger engageable with said recess, overcenterretaining means for retaining the latch in its latched position, andmeans associated with said latching finger and said recess to overridesaid retaining means and move said latching finger to its unlatchedposition upon the application of a manual force on said handles urgingthem to an open position.
 2. The tool of claim 1 wherein the latchingfinger has a wedge-shaped engaging surface, and the manual openingmovement of said handles imposes a force thereon at a small acute anglewhen the latch is in a latched position.
 3. The tool of claim 2 whereinthe engaging surface of said latching finger is formed on a radius ofcurvature having a center which is offset from the pivot axis of thelatch.
 4. The tool of claim 3 wherein the radius of curvature of theengaging surface of said latching finger is less than its distance fromthe axis of said latch.
 5. The device of claim 3 in which the forceapplied to said latching finger upon the application of a force urgingthe handles to an open position is directed at an angle of about 45*thereto and is offset from a line passing through the center ofcurvature thereof and the axis of said latch.
 6. The tool of claim 3wherein the rotary latch is journaled in an aperture and is providedwith resilient depending leg means biased against a non-circular wall ofsaid aperture and the contacting portion of said leg means is rotatedslightly past a line which is perpendicular to said non-circular walland passes through the axis of rotation of said latch.